Author: kib Date: Tue Sep 15 22:13:21 2020 New Revision: 365786 URL: https://svnweb.freebsd.org/changeset/base/365786
Log: Microoptimize tmpfs node ref/unref by using atomics. Avoid tmpfs mount and node locks when ref count is greater than zero, which is the case until node is being destroyed by unlink or unmount. Reviewed by: markj Tested by: pho Sponsored by: The FreeBSD Foundation Differential revision: https://reviews.freebsd.org/D26346 Modified: head/sys/fs/tmpfs/tmpfs.h head/sys/fs/tmpfs/tmpfs_subr.c head/sys/fs/tmpfs/tmpfs_vnops.c Modified: head/sys/fs/tmpfs/tmpfs.h ============================================================================== --- head/sys/fs/tmpfs/tmpfs.h Tue Sep 15 22:06:36 2020 (r365785) +++ head/sys/fs/tmpfs/tmpfs.h Tue Sep 15 22:13:21 2020 (r365786) @@ -228,7 +228,7 @@ struct tmpfs_node { int tn_vpstate; /* (i) */ /* Transient refcounter on this node. */ - u_int tn_refcount; /* (m) + (i) */ + u_int tn_refcount; /* 0<->1 (m) + (i) */ /* misc data field for different tn_type node */ union { @@ -412,7 +412,6 @@ struct tmpfs_dir_cursor { */ void tmpfs_ref_node(struct tmpfs_node *node); -void tmpfs_ref_node_locked(struct tmpfs_node *node); int tmpfs_alloc_node(struct mount *mp, struct tmpfs_mount *, enum vtype, uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *, const char *, dev_t, struct tmpfs_node **); Modified: head/sys/fs/tmpfs/tmpfs_subr.c ============================================================================== --- head/sys/fs/tmpfs/tmpfs_subr.c Tue Sep 15 22:06:36 2020 (r365785) +++ head/sys/fs/tmpfs/tmpfs_subr.c Tue Sep 15 22:13:21 2020 (r365786) @@ -49,6 +49,7 @@ __FBSDID("$FreeBSD$"); #include <sys/priv.h> #include <sys/proc.h> #include <sys/random.h> +#include <sys/refcount.h> #include <sys/rwlock.h> #include <sys/stat.h> #include <sys/sysctl.h> @@ -211,23 +212,17 @@ tmpfs_pages_check_avail(struct tmpfs_mount *tmp, size_ void tmpfs_ref_node(struct tmpfs_node *node) { +#ifdef INVARIANTS + u_int old; - TMPFS_NODE_LOCK(node); - tmpfs_ref_node_locked(node); - TMPFS_NODE_UNLOCK(node); + old = +#endif + refcount_acquire(&node->tn_refcount); +#ifdef INVARIANTS + KASSERT(old > 0, ("node %p zero refcount", node)); +#endif } -void -tmpfs_ref_node_locked(struct tmpfs_node *node) -{ - - TMPFS_NODE_ASSERT_LOCKED(node); - KASSERT(node->tn_refcount > 0, ("node %p zero refcount", node)); - KASSERT(node->tn_refcount < UINT_MAX, ("node %p refcount %u", node, - node->tn_refcount)); - node->tn_refcount++; -} - /* * Allocates a new node of type 'type' inside the 'tmp' mount point, with * its owner set to 'uid', its group to 'gid' and its mode set to 'mode', @@ -370,6 +365,8 @@ tmpfs_alloc_node(struct mount *mp, struct tmpfs_mount void tmpfs_free_node(struct tmpfs_mount *tmp, struct tmpfs_node *node) { + if (refcount_release_if_not_last(&node->tn_refcount)) + return; TMPFS_LOCK(tmp); TMPFS_NODE_LOCK(node); @@ -384,19 +381,19 @@ tmpfs_free_node_locked(struct tmpfs_mount *tmp, struct bool detach) { vm_object_t uobj; + bool last; TMPFS_MP_ASSERT_LOCKED(tmp); TMPFS_NODE_ASSERT_LOCKED(node); - KASSERT(node->tn_refcount > 0, ("node %p refcount zero", node)); - node->tn_refcount--; - if (node->tn_attached && (detach || node->tn_refcount == 0)) { + last = refcount_release(&node->tn_refcount); + if (node->tn_attached && (detach || last)) { MPASS(tmp->tm_nodes_inuse > 0); tmp->tm_nodes_inuse--; LIST_REMOVE(node, tn_entries); node->tn_attached = false; } - if (node->tn_refcount > 0) + if (!last) return (false); #ifdef INVARIANTS @@ -596,7 +593,7 @@ tmpfs_alloc_vp(struct mount *mp, struct tmpfs_node *no error = 0; tm = VFS_TO_TMPFS(mp); TMPFS_NODE_LOCK(node); - tmpfs_ref_node_locked(node); + tmpfs_ref_node(node); loop: TMPFS_NODE_ASSERT_LOCKED(node); if ((vp = node->tn_vnode) != NULL) { Modified: head/sys/fs/tmpfs/tmpfs_vnops.c ============================================================================== --- head/sys/fs/tmpfs/tmpfs_vnops.c Tue Sep 15 22:06:36 2020 (r365785) +++ head/sys/fs/tmpfs/tmpfs_vnops.c Tue Sep 15 22:13:21 2020 (r365786) @@ -1663,7 +1663,7 @@ restart: if (tnp->tn_type != VDIR) continue; TMPFS_NODE_LOCK(tnp); - tmpfs_ref_node_locked(tnp); + tmpfs_ref_node(tnp); /* * tn_vnode cannot be instantiated while we hold the _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
